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Nature Notebook – Cecropia Moth

A spot frequently passed by naturalists on the nature center grounds exposed a cecropia moth cocoon last week. The cecropia moth is the largest moth in North America, and the fact that we did not see this 4-inch cocoon after months of passing the same dogwood tree, is a triumph of its stealthiness.

The cryptic cocoon was made in the fall by the larva, or caterpillar, after feeding for months on host plant trees such as beeches, elms, maples, poplars, or dogwoods. Cecropia’s are silk moths and use their self-produced silk to create their papery, tough, brown cocoon, characteristically attached to a twig on one side. Sometimes, leaves or twigs may even by incorporated into its structure.

The caterpillar must beware ichneumon wasps, among other predators. The wasp will parasitize the caterpillar while it spins its cocoon and actually lay its eggs inside of the caterpillar.

If the caterpillar is not parasitized, the double-layer cocoon protects the caterpillar, which changes into a pupa, and then in May or June, the 5-7 inch adults emerge and fly.